The Babylonians in ancient Egypt made this decision due to the fact that they did most of their astronomical calculations using what is called the sexagesimal system. This mathematical system based on the number 60 helped making calculations easier and more convenient because the number 60 is divisable by 2, 3, 4, 5, 6, 10, 12, 15, and 30. The first sexagesimal place (which is the equivelant to a decimal place in a 10-base numbering system) is what we refer to as a minute and the second sexagesimal place is called a second. Thus we have minutes and seconds. Reference used from "A History of Ancient Mathematical Astronomy, O. Neugebauer, Springer-Verlag, Berlin, 1975."

I won't argue with Scotty, but I will ask what in the heck were those Babylonians doin' in ancient Egypt? They had a perfectly viable civilization long before Egypt was more than a landing spot on the Nile. I will argue with O. Neugebauer. O and the other experts like to marvel on the number 60, as if it was the only number divisible by other numbers. As if the Babylonians had a big meeting to pick THE number, " I nominate 80, divisible by 2, 4, 5,8, 10, 20, and 40." ( O. Neugebaur, O. Neugebaur, your reas'ning conv'luted. ") The Babylonians, wherever they were vacationing, had ten fingers and counted most things by tens or decimally, what the experts all seem to overlook is a number way down in the factors of 60. 12. Most years have 12 lunar cycles, then the climate conditions recycle. A lot of societies back then used the lunar cycle to measure a year. The Jews still do, which is why Easter doesn't have a set date. 12 became an important even mystical number. (A cube, one of the 'perfect shapes', has six sides , maybe two cubes are more magical than one. I dunno I haven.t thought that out yet.)When the Babylonians decided to divide up the circle into measurable segments they were probably pleasantly surprised to find that 12 segments were easy to do with just a few simple tools as compared to ten. Cut it in half, then cut it at right angles to that,now halve those and you got eighths. Some cultures were happy with the eighths as a measurement, even of time. They called them 'watches' , the Romans used them, Shakespeare speaks of them, navies still have "eight bells." As far as time goes that was good enuff f even for Babylonians, but they wanted somethin more precise for circles, tenths were hard to do with a simple straight edge and compass , further splitting into halves with diameters to get 16ths required a even more precision ,but splitting each of those quarters into three parts was easy. Eventually because of relations between 12 and 10 (way more interesting than the characteristics of 60) we got 360 degrees in a circles. Now so far that's got nothin to do with time. YET. Back then they measured time with sundials, other methods, sand glass, water clock etc were calibrated against sundials. Sundials are more or less of a semicircle, depending on where you are. Circles are easily divided into 12ths, 12 is a magic number. 12 periods in the daylight, 12 at night. Course in some places day time summer 12ths were longer than winter ones. Now fast forward to the invention of the clock, because of the mechanics of gears and wheels the clock face became a circle. They had to divide the circle. Ah! 12ths are easy the Babylonians figured that out. What do we call it? Lo and behold "hour" means 1/12 of a circle! ( 24 hour clocks were and still are available they are just too close together, hard to read.) And then the hour as a part of a circle had already been divided into 60 "minutes" by the circle fans and the minute into 60 "seconds" ( yeah its 12 X 5, but it's still relations atween 12 and 10). So that is why the clock is 12 hours , 60 minutes, 60 seconds. Later on they divided the earth into HOURS of longitude, earths a circle seen from above the North Pole so it was divived into 12 hours. Later on that got confusing so they just decided to divide it into degrees 360 in a circle ( that old divide the circle with compass and straight edge thing) (The british had a stronger navy so 0* [ hey no degree symbol!)]went thru Geenwich and not Paris.) That's got nothin to do with time, except, yeah it really does. "Hey Where are we?" "I dunno what time is it? And why the heck are all these Babylonians tryin to swipe my piece of pizza ?"